Showing papers by "Miguel Castro published in 2022"

Highly Regular Hexagonally-Arranged Nanostructures on Ni-W Alloy Tapes upon Irradiation with Ultrashort UV Laser Pulses

Abstract: Nickel tungsten alloy tapes (Ni—5 at% W, 10 mm wide, 80 µm thick, biaxially textured) used in second-generation high temperature superconductor (2G-HTS) technology were laser-processed in air with ultraviolet ps-laser pulses (355 nm wavelength, 300 ps pulse duration, 250–800 kHz pulse repetition frequency). By employing optimized surface scan-processing strategies, various laser-generated periodic surface structures were generated on the tapes. Particularly, distinct surface microstructures and nanostructures were formed. These included sub-wavelength-sized highly-regular hexagonally-arranged nano-protrusions, wavelength-sized line-grating-like laser-induced periodic surface structures (LIPSS, ripples), and larger irregular pyramidal microstructures. The induced surface morphology was characterized in depth by electron-based techniques, including scanning electron microscopy (SEM), electron back scatter diffraction (EBSD), cross-sectional transmission electron microscopy (STEM/TEM) and energy dispersive X-ray spectrometry (EDS). The in-depth EBSD crystallographic analyses indicated a significant impact of the material initial grain orientation on the type of surface nanostructure and microstructure formed upon laser irradiation. Special emphasis was laid on high-resolution material analysis of the hexagonally-arranged nano-protrusions. Their formation mechanism is discussed on the basis of the interplay between electromagnetic scattering effects followed by hydrodynamic matter re-organization after the laser exposure. The temperature stability of the hexagonally-arranged nano-protrusion was explored in post-irradiation thermal annealing experiments, in order to qualify their suitability in 2G-HTS fabrication technology with initial steps deposition temperatures in the range of 773–873 K.

4-Phenylcoumarin (4-PC) Glucoside from Exostema caribaeum as Corrosion Inhibitor in 3% NaCl Saturated with CO2 in AISI 1018 Steel: Experimental and Theoretical Study

Abstract: The corrosion inhibition of 5-O-β-D-glucopyranosyl-7-methoxy-3′,4′-dihydroxy-4-phenylcoumarin (4-PC) in AISI 1018 steel immersed in 3% NaCl + CO2 was studied by electrochemical impedance spectroscopy (EIS). The results showed that, at just 10 ppm, 4-PC exerted protection against corrosion with ղ = 90% and 97% at 100 rpm. At static conditions, the polarization curves indicated that, at 5 ppm, the inhibitor presented anodic behavior, while at 10 and 50 ppm, there was a cathodic-type inhibitor. The inhibitor adsorption was demonstrated to be chemisorption, according to the Langmuir isotherm for 100 and 500 rpm. By means of SEM–EDS, the corrosion inhibition was demonstrated, as well as the fact that the organic compound was effective for up to 72 h of immersion. At static conditions, dispersion-corrected density functional theory results reveal that the chemical bonds established by the phenyl group of 4-PC are responsible of the chemisorption on the steel surface. According with Fukui reactivity indices, the molecules adsorbed on the metal surface provide a protective cover against nucleophilic and electrophilic attacks, pointing to the corrosion inhibition properties of 4-PC.

Tumor specifically internalizing peptide ‘HN-1’: Targeting the putative receptor retinoblastoma-regulated discoidin domain receptor 1 involved in metastasis

Abstract: BACKGROUND Less than 0.5% of intravenously injected drugs reach tumors, contributing to side effects. To limit damage to healthy cells, various delivery vectors have been formulated; yet, previously developed vectors suffer from poor penetration into solid tumors. This issue was resolved by the discovery of HN-1 peptide isolated via biopanning a phage-display library. HN-1 targets human head and neck squamous cell carcinoma (HNSCC) (breast, thyroid; potentially lung, cervix, uterine, colon cancer), translocates across the cell membrane, and efficiently infiltrates solid tumors. HN-1 peptide has been conjugated to various anticancer drugs and imaging agents though the identity of its receptor remained enigmatic. AIM To decipher the clues that pointed to retinoblastoma (Rb)-regulated discoidin-domain receptor 1 as the putative receptor for HN-1 is described. METHODS HN-1 peptide was synthesized and purified using reverse-phase high-performance liquid chromatography and gel electrophoresis. The predicted mass was confirmed by mass spectroscopy. To image the 3-dimensional structure of HN-1 peptide, PyMOL was used. Molecular modeling was also performed with PEP-FOLD3 software via RPBS bioinformatics web portal (INSERM, France). The immunohistochemistry results of discoidin domain receptor 1 (DDR1) protein were obtained from the publicly accessible database in the Human Protein Atlas portal, which contained the images of immunohistochemically labeled human cancers and the corresponding normal tissues. RESULTS The clues that led to DDR1 involved in metastasis as the putative receptor mediating HN-1 endocytosis are the following: (1) HN-1 is internalized in phosphate-buffered saline and its uptake is competitively inhibited; (2) HN-1 (TSPLNIHNGQKL) exhibits similarity with a stretch of amino acids in alpha5 beta3 integrin (KLLITIHDRKEF). Aside from two identical residues (Ile-His) in the middle, the overall distribution of polar and nonpolar residues throughout the sequences is nearly identical. As HN-1 sequence lacks the Arg-Gly-Asp motif recognized by integrins, HN-1 may interact with an "integrin-like" molecule. The tertiary structure of both peptides showed similarity at the 3-dimensional level; (3) HN-1 is internalized by attached cells but not by suspended cells. As culture plates are typically coated with collagen, collagen-binding receptor (expressed by adherent but not suspended cells) may represent the receptor for HN-1; (4) DDR1 is highly expressed in head and neck cancer (or breast cancer) targeted by HN-1; (5) Upon activation by collagen, DDR1 becomes internalized and compartmentalized in endosomes consistent with the determination of ’energy-dependent clathrin-mediated endocytosis’ as the HN-1 entry route and the identification of HN-1 entrapped vesicles as endosomes; and (6) DDR1 is essential for the development of mammary glands consistent with the common embryonic lineage rationale used to identify breast cancer as an additional target of HN-1. In summary, collagen-activated tyrosine kinase receptor DDR1 overexpressed in HNSCC assumes a critical role in metastasis. Further studies are warranted to assess HN-1 peptide’s interaction with DDR1 and the therapeutic potential of treating metastatic cancer. Additionally, advances in delivery (conformation, endocytic mechanism, repertoire of targeted cancers of HN-1 peptide), tracking (HN-1 conjugated imaging agents), and activity (HN-1 conjugated therapeutic agents) are described. CONCLUSION The discovery of DDR1 as HN-1 peptide’s putative receptor represents a significant advance as it enables identification of metastatic cancers or clinical application of previously developed therapeutics to block metastasis.

Effect of CaS/DMSO dispersions in the cytoskeleton and focal adhesion points of human skin adherent benign and melanoma cells

Abstract: CaS/DMSO has been the subject of work in our group because it dissociates spontaneously in proton rich environments to produce Ca2+ ions and H2S. Extracellular Ca2+ concentrations in the neighbourhood of 500nM can induce apoptosis. Smaller concentrations of H2S can also induce apoptosis. We present here our efforts to establish the effect of CaS clusters in the cytoskeleton and focal adhesion points of human skin adherent benign and melanoma cells. We hypothesize that if the CaS nanoclusters can induce programmed death, then we will observe a significant impact in the focal adhesion points of cancer cells. We have studied the effect of DMSO and diluted CaS/DMSO on the focal adhesion points and cytoskeleton of cancer and benign cells using a digital confocal microscope. Anti‐vinculin monoclonal antibody and FITC‐conjugated secondary antibodies were used to detect vinculin in the cell environment. Vinculin expression was found to increase in benign cells in the first 24 and 48 hours of incubation with 1% DMSO. Comparison with control experiments the DMSO appears to localize vinculin expression around benign cell nuclei as well as the boundaries of the cytoskeleton. The CaS/DMSO increase the focal adhesion points of the adherent benign cells. In contrast, vinculin expression decreased in human melanoma fibroblasts cells incubated with 1% DMSO‐ as compared to the corresponding melanoma control cells‐ in the first 24 hours. In contrast, vinculin expression of the melanoma cells increased and de‐localized to the cell boundary edges in the first 24 hours when incubated with the CaS/DMSO. The vinculin expression in the melanoma cells incubated with 1% DMSO was found to increase significantly 48 hours as compared to the control. As with the benign cells, the melanoma cells vinculin expression was found to be more localized around the nuclei at the 48‐hour mark as compared to the first 24 hours. Vinculin expression could barely be detected in the fluorescence microscope following incubation of the melanoma cells with the CaS dispersion for 48 hours. Thus, in contrast to the benign cells, the CaS/DMSO reduce the focal adhesion points of the adherent melanoma cell. TRITC conjugated phalloidin antibody was employed to study the effect of DMSO in the F‐actin associated with the cytoskeleton of human benign and melanoma adherent skin cells. The F‐actin expression in the benign cells incubated with 1 % DMSO was found to decrease in the first 24 hours and then to increase significantly 48 hours following incubations as compared to the control. The CaS/DMSO does not seem to have any noticeable effect in the benign cells following 24 or 48 hours of incubation as compared to the control. We are led to control that the CaS/DMSO does not affect the benign skin cells cytoskeleton. The F‐actin expression changed from a protein with linear‐like to branch morphology in the melanoma cells incubated with DMSO. The CaS/DMSO increased the F‐actin branching but reduced its overall expression. In summary the results indicate that CaS does not affect adversely the normal cell cytoskeleton and focal adhesion point expression in benign cells, but it significantly reduces the vinculin expression in human melanoma adherent cells. Furthermore, as these effects are not observed in the benign cells, we are led to conclude that the difference in extracellular pH between human skin benign and melanoma cancer cells results in the observed selectivity to affect the focal adhesion point.